Lubricating bearing surface



bearing surfaces,

Patented Feb. 7, 1939 PATENT OFFICE LUBRICATING BEARING SURFACE Troy Lee Cantrell and James Otho Turner, musdowne, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Application June 5, 1936, Serial No. 83,761

2 Claims.

This invention relates to improved methods of lubricating bearing surfaces in internal combustion engines when subjected to conditions of operation which comprises maintaining between one of which is an alloy formed chiefly of a metal of the class consisting of cadmium and copper, a mineral lubricating oil which initially produces an effective lubricating action but which would normally tend to corrode the aforesaid alloy and maintaining the effectiveness of the lubricating 'oil by incorporating a parahydroxy meta-alkoxy benzaldehyde in a small but sufficient proportion substantially to retard the corrosion; all as more fully hereinafter set forth and as claimed.

Recent developments in the design of mechanical equipment for generating and transmitting power, and particularly in the automotive field, have necessitated new bearing metals with special properties. Among these new bearing materials are binary and ternary alloys of the metals mentioned above. Cadmium-silver-copper, cadmium-nickel-copper, copper-lead-nickel, etc., alloys I are in use. One ternary alloy currently used in automobile engines is an alloy of cadmium with minor amounts of both silver and copper. Under the conditions imposed by modern engineering design, these new alloy bearings are commonly subjected to more severe operatingconditions 0 than were usual in the older art: to higher bearing loads, higher rubbing speeds and higher temperature's of operation. It is found that in actual use under these conditions there often develops quite serious destructive action on the bearing surface by mineral lubricating oils, even by those standard commercial oils giving particularly good results with the older bearing metals under the earlier operating conditions. The destruction of the bearing metal probably results from action of deterioration products developed in the oil. An' object achieved in the present invention is the production of lubricating-oils improved for these newer conditions of use and which. are characterized'by reduction or elimination of destructive action on the newer bearing metals by deterioration products in the oil. y

We have discovered that para-hydroxy metaalkoxy benzaldehyde incorporated with lubricants, are capable of achieving the objects of the present invention, the meta-methoxy compound (vanillin) being particularly effective. By addingsmall amounts of such compounds to the mineral oil or lubricant, we obtain improved lubricating compositions which satisfactorily lubricates the said alloy bearings. Incorporated in mineral 011,

these compounds retard destruction of the hearing metal. The character and amount of added improvement agent, here employed, are such that the initial properties of the oil, such as viscosity, gravity, color, etc., are not substantially altered. 5 Thus, by the present invention, certain. properties of the lubricant are improved without sacrificing the other desirable properties of the lubricating oil.

We obtain improved mineral oils and lubricants 1o suitable for lubricating such bearings under a wide range of service conditions. The new compounded lubricant satisfactorily lubricates the new alloy bearings even under high unit pressure, high bearing speeds and high operating tempera-tures. When prepared from suitable motor oils, the present improved compositions are excellent lubricants for the modern automobile engine. They satisfactorily lubricate the bearings without I any destruction of the special bearing alloys now used, even in the presence of a free circulation of air.

Ordinarily between 0.05 and 0.50 per cent by weight of these compounds are sufllcient to produce a satisfactory lubricant. However, in some cases larger amounts of the improvement agent may be employed, for instance, with the less stable mineral lubricating oils. As much as 1 per cent may sometimes be added with advantage. The particular proportions depend upon the par- 0 ticular agent and lubricating base employed and the particular type of lubricant desired.

The agents here employed to improve and stabilize the mineral oil and lubricating compositions may be represented by the following formula wherein R represents alkyl group. As a class, these hydroxy-alkoxy aldehyde compounds of benzene are soluble and miscible with mineral oils in suflicient proportion to efiect our desired improvement in the oil.

The improvement agents here employed are well known chemical compounds and are cheink 5 cally known also as 1-methanal-3-alkoxy-4-hydroxy-benzenes. They may be prepared by various methods. For instance, vanillin (1,-methanal-3-methoxy-4-hydroxy benzene), is industrially manufactured on a large scale by the 0111- dation of isoeugenol. Vanillin is also known as para-hydroxy-meta-methoxy benzaldehyde and may also be prepared from other starting materials such as protocatechuic aldehyde (3:4-dihydroxy benzaldehyde) and the mono-methyl ether of pyrocatechin (ortho-methoxy phenol) by appropriate methods known in the art. Vanillin is much used as a flavoring extract and for many other purposes, but heretofore its ability to improve mineral oils has been unknown.

Vanillin is a colorless, crystalline solid with a familiar characteristic odor and flavor. It has a. melting point of 80-81 C. It is slightly soluble in water and is very soluble in ether and alcohol. It has a limited solubility in hydrocarbon oils, such as mineral or petroleum oils. However. -it is sufficiently soluble in petroleum lubricating oils for the purpose of the present invention. A permanent solution of 0.20 per cent by weight of vanillin in the usual lubricating oils can be readily prepared and the solution so obtained is an improved lubricant.

In lieu of vanillin, other alkoxy derivatives of para-hydroxy benzaldehyde may be employed, such as the ethoxy or butyoxy (secondary or tertiary butyl) compounds. The ethoxy compound has the following formula and melting point:

(Melting point 7778 C.)

O-GHzCH:

The secondary butyoxy compound has the following formula:

The normal and tertiary butyl compounds may be used instead of the secondary compound; likewise with the propyl compounds, etc. The tertiary butyl ether has the following formula:

The above compounds may be used in the practice of the present invention, as shown in more detail post.

Generally, the hydroxy-alkoxy benzaldehydes here employed are readily miscible and compatible with petroleum oils in the percentages necessary for the present purposes. They may be incorporated with the mineral oil or lubricating base in any suitable manner. They may be dissolved in the oil by simply mixing them with the oil and slightly warming with agitation to obtain uniform lubricants. Warming to temperatures between F. and 180 F. is sufllcient. With the heavier and more viscous lubricating oils this warming is advantageous since the heating lowers the viscosity of the oil and so facilicommercial bearing shells.

tates the blending- In some cases, these compounds may be dissolved in suitable volatile solvents and the solution added to the oil, the solvent being subsequently distilled off. Also, they may be first dissolved in a suitable lubricating oil to form a master batch which is subsequently blended with more lubricating oil to give a range of lubricating compositions as desired. Likewise the compounded lubricant may be converted into thickened compositions or greases in any of the usual ways. The improvement agent may be directly added to metal soap greases or other compounded lubricants in which a petroleum oil is the lubricating base.

In the practice of the present invention any suitable mineral lubricating oil base may be employed, either heavy or light oil. Ordinarily it is best to select a good grade of mineral lubrieating oil which has suitable initial properties for the particular lubrication requirement. Then the addition of the para-hydroxy meta-alkoxy benzaldehyde produces the additional desired characteristics of restraining their destructiveness toward the newer alloy bearing metals, etc. That is, petroleum oils and lubricants of the usual grades may be employed in practicing this invention. The oils falling within the well known S. A. E. classifications are among those which can advantageously be improved by our invention. Likewise, special lubricants such as obtained by blending certain non-petroleum oils with mineral oil may be improved by the addition of vanillin or its homologues.

The deterioration of bearings by particular oils under drastic service conditions may be readily observed by visual-inspection, but a special laboratory test is necessary to readily and quickly determine corrosion and pitting on a standard, comparable and reproducible basis and to readily evaluate commercial lubricants for such alloy bearings. We have devised a satisfactory accelerated test procedure which is as follows.

An alloy bearing shell of certain commonly used standard dimensions is submerged in 300 cc. of the oil or oil composition in a400 cc. pyrex beaker and heated in a thermostatically controlled oil bath to C. (347 F.) and air, at the rate-of 2000 cc. per hour, is bubbled through the oil in contact with the bearing shell. At the end of 48 and 96 hours, the loss of weight and the condition of the bearing shell are determined. This test will hereinafter be referred to as our standard laboratory test.

In determining the loss in weight the bearing shell is washed free of oil and dried before weighing.

When determining the eifectivenes's of various improvement agents the usual procedure is to run a "blank test simultaneously with the oil composition being tested, employing for that purpose a sample of the untreated oil.

In such tests it is advantageous to employ These shells comprise a suitable metal backing faced with the alloy bearing metal. In the above test, the air is bubbled against the alloy bearing face. I' this way, the actual bearing face is subjected to severe deteriorative conditions. By comparison of the results of such tests with actual service tests, we have found them to be in substantial agreement as to the suitability of particular lubricants.

In testing our lubricants, we have employed, among others, bearings of the following approximate composition:

1. Cadmium-silver alloy, C-S 7610.

Metal Percent Cadmium Silver Copperv-noo 2. Lead-copper alloy, 9020 CA.

Metal Percent Tmari 45 Copper 53 Nickel 2 The properties of the original andimproved motor oil so obtained are as follows:

Such alloys are used in the tests of illustrative improved lubricants given post. In such tests the loss in weight, while not extremely high when expressed as per cent loss, is nevertheless very significant, as the bearing shells used have an alloy facing of only .008 inch to .012 inch thickness on a highly resistant backing and the observed losses in the reported tests often represent a loss of the order of ten per cent of the alloy facing.

The specific examples andtests given post are illustrative of detail embodiments of the present invention.

Example 1.1000 gallons (approximately 7200 pounds) of Pennsylvania motor oil S. A. E. 10 grade are warmed to 160 F. and 3.6 pounds of vanillin (0.05 per cent by weight) are added thereto, and the mixture is agitated until a uniform blend is obtainedj about 1 hour being required. The improved motor oil is then cooled and packaged in suitable containers.

The properties of the original and improved motor oil so obtained are as follows:

From the above table it is clear that the addition of the vanillin does not substantially change the ordinary properties of the oil. However, the improved lubricant obtained is substantially nondestructive to alloy bearings.

When tested by the standard test given ante using a commercial bearing shell faced with the cadmium-silver alloy C-S 7610, the following results are obtained in the 48 hour run:

Table B Bearing shell weight-' Original on Egggggi Grams Grams Before oxidation. 27. 7876 p 35. 8965 After oxidation. 27. 3670 35. 8930 Total change -o.42'05 -o. 0035 Comment Significant loss. Insignificant Appearance (alter test) Badly etched No change.

and pitted.

From the above results, the beneficial effect of the vanillin as an improvement agent for the Table Original 011 Gravity: APT 31.4 31.4 Viscosity, SUV:

59 59' 440 440 505 505 5 2. 5 2. 5 0. 13 0. l3 nil -nil v Sat sfactory Satisfactory This improved lubricant when tested in the same manner as given in Example 1, gave the following results:

Table D Bearing shell weightflgg g'gg Grams Grams Before oxidation 26. 7291 27. 4533 After oxidation 26. 4205 27. 4523 Total change -0. 3086 -0. 0010 Appearance (after test) Badly etched No change and pitted may be selected according to. the type of final lubricant to be produced. For instance, any of the usual greases or the usual blends of mineral and blown fatty oils may be employed as a lubricating base in making improved lubricants of those types. The addition of the vanillin to these lubricating bases produces a. like improvement.

Vanillin alone is a highly effective improvement agent for mineral lubricating oil, and we also find it useful as an assistant to numerous other so called improvement agents, and its use in conjunction with other so called improvement agents which have unpleasant odors is especially desirable because the pleasant odor of vanillin tends to screen any unpleasant odors which may be present.

The use as improvement agents of materials which contain either sulfur or chlorine or both in their chemical constitution, is known. Both sulfur and chlorine present in this manner are found undesirable under certain conditions of use, and our use of vanillin as an improvement agent for mineral lubricating oils completely avoids the undesirable effects just referred to.

The addition of vanillin to lubricating oil not only has utility, as described at length herein, but it also imparts tothe oil a pleasant characteristic nonpetroleum odor.

When incorporating the vanillin, etc., in a grease composition or like thickened lubricant mechanical agitators rather than a current of air may beemployed to obtain uniform mixing and blending. That is, the vanillin and grease may be compounded in the usual mixers, such as blade mixers equipped -with heating jackets. However, in making such greases, the vanillin may first be incorporated with the oil base according to the procedure of Example 1 and then the metal soap or other thickening agent added to the thickened oil in the ordinary way to produce the desired grease composition. In other words the improved mineral oils of the present invention may be used in lieu of the ordinary oils in making special lubricating compositions such as greases, etc. v

As stated ante, the incorporation of these hydroxy alkoxy benzaldehydes with the lubricat ing base produces several improvements in the final lubricant without deleterlously affecting the desirable properties. While the exact reasons for the improvements obtained here are not fully known, we are satisfied with observing and utilizing the actual improvements obtained by adding and incorporating vanillin or its homologues with commercial lubricants.

What we claim is:

1. A method of lubricating bearing surfaces in internal combustion engines when subjected to conditions of operation which comprises maintaining between bearing surfaces, one of which is an alloy formed chiefly of a metal selected from the class consisting of cadmium and copper, a film of lubricating oil which initially produces an effective lubricating action but which would normally tend to corrode the aforesaid alloy, and maintaining the effectiveness of the lubricating oil by incorporating therein between 0.05 and 0.50 percent by weight on the oil of a hydroxyalkoxy benzaldehyde.

2. A method of lubricating bearing surfaces in internal combustion engines when subjected to conditions of operation which comprises maintaining between bearing surfaces, one of which is an alloy formed chiefly of a metal selected from the class consisting of cadmium and copper, a film of lubricating oil which initially produces an effective lubricating action but which would normally tend .to corrode the aforesaid alloy and maintaining the eifectiveness of the lubricating oil by incorporating therein vanillin in a small but suflicient proportion substantially to retard the corrosion.

I'ROY LEE CANTRELL. JAMES OTHO TURNER. 

